Alfalfa can weather drought, but might yield less

Growers may find that although alfalfa can weather the current extreme heat and drought conditions from a quality standpoint, there will be less of it, an Ohio State University Extension educator says.

An established alfalfa plant has a deep taproot allowing it to extract moisture from the soil and continue growing even under drought conditions, said Rory Lewandowski, an agricultural and natural resources educator for OSU Extension.

While the plants can go into a prolonged dormancy in drought conditions and still recover when it rains, the short-term forecast calls for continued hot, dry weather. So growers whose plants have regrowth beginning to bloom at 4 to 6 inches need to know that there will be little additional tonnage gained by delaying harvest, Lewandowski said.

“The bottom line is that drought-induced moisture stress can cause plants to move through maturity stages quicker, and plants bloom sooner on fewer and shorter stems,” he said. “The key here is that we’re not going to have a lot of growth. So while quality may be improved, quantity is reduced.”

With this in mind, Lewandowski said growers might want to consider letting the plants approach 100 percent bloom before harvesting to allow the plant to build nonstructural carbohydrate reserves.

Growers who decide to cut their alfalfa stand under drought conditions should cut them at the normal height, which will allow them to gain optimum yield, he said.

But some growers might find that there isn’t enough quantity to make a machine harvest cost effective. “In those cases, it’s much more economical to let livestock salvage a low-tonnage yield by grazing the alfalfa,” Lewandowski said.

Those who choose that option need to take precautions to prevent livestock bloat, which include not grazing alfalfa when dew is on it, making sure stocking density is high enough to prevent animals from grazing only the tops of plants, and potentially using a bloat preventive.

“Growers are recognizing that in a drought situation, they have to think about different management strategies,” Lewandowski said. “We’re seeing above-average temperatures and below-average rainfall, which is not a good combination for anyone.

“From our forage crops, agronomic crops and field crops, everyone is feeling the stress from this lack of moisture and extreme heat. So some producers are beginning to make plans, including anticipating where they can find some other hay sources and thinking about what this will mean for fall and winter feeding.”